This invention relates to medical instruments and methods for tying knots in a suture, particularly medical instruments and methods for tying knots in a suture at intracorporeal positions during least invasive surgery.
Least invasive surgery includes laparoscopic, endoscopic and orthoscopic surgeries. In performing laparoscopic surgery, for example, procedures are performed in the abdominal cavity by making a small incision through several layers of tissue, including the outer layer of skin called the epidermis, a layer of fat beneath the epidermis, a layer of abdominal muscle tissue beneath the fat layer and the lining of the abdominal cavity called the peritoneum. A trocar is inserted through the incision and medical instruments are introduced into the abdominal cavity therethrough. The surgeon performs procedures inside the cavity by manipulating the medical instruments from outside the patient while viewing the manipulations using a closed circuit monitor connected to an imaging device called a laparoscope that is inserted into the cavity. By using such equipment and procedures, laparoscopic surgery generally results in less trauma to the patient and, consequently, a more rapid recovery than with conventional open surgery. Similar advantages apply to other forms of least invasive surgery.
During least invasive surgery, it is necessary to close incisions made in intracorporeal tissue. Typically, each incision is closed by applying and tying a suture across the incision. In doing so it is generally desirable to use instruments that are easily manipulable and procedures that are efficient, so as to avoid unnecessary trauma to the patient.
Known instruments and procedures for tying sutures in least invasive surgery have a variety of forms, each having significant limitations. Noda et al. U.S. Pat. No. 5,129,912 ("Noda"), for example, discloses a knot tying device comprising a shaft that carries, at its distal end, a removable needle and a removable pre-formed knotted loop of suture. The needle is attached to one end of the knotted loop and the other end of the knotted loop extends to the proximal end of the shaft where it is attached to a tensioning device. In use, the instrument is introduced into the body cavity to a position proximate the incision to be closed, whereupon a second instrument is used to remove the needle, pass it through tissue on either side of the incision and then through the knotted loop, the knotted loop then being tightened using the tensioning device. Noda's instrument is undesirably limited in that it requires use of pre-formed knotted loops. Moreover, it requires manipulation of the needle to perform complex movements in tying knots. In addition, it is not designed to be used to tie two lengths of suture, as in a square knot.
Because conventional knot tying instruments and methods for their use have inherent limitations, a need exists for an improved instrument and method for tying knots in suture at intracorporeal positions during least invasive surgery.